The present invention relates to magnetic storage apparatus, particularly of the mass store type employing a plurality of flexible record disks and particularly to means for identifying which disk is in juxtaposition for transducing access.
ROTATING DISK TYPE ELECTRONIC MEMORIES HAVE BEEN USED FOR THE LAST SEVERAL YEARS. While most of these memories have employed the so-called rigid record disk, later developments have shown that the utilization of flexible record disks may provide increases in volumetric efficiency; that is, more recording can be achieved in less volume when apparatus employs flexible record disks than when employing rigid record disks. Such flexible record disks are employed in a coaxial stack of such disks having a spacing less than that required for transducing access. Apparatus is employed for splitting the stack, that is, partially axially separating a selected two of the flexible disks to provide a transducing access opening. An example of such apparatus, no limitation thereto intended, is shown by Barbeau et al., in U.S. Pat. No. 3,852,820.
One of the problems of peripherally accessing a stack of flexible record disks is caused by the dynamics of the disk rotation, particularly the changes of axial position of the disk edge with rotation such as caused by flutter, wow, and changes in fluid dynamics within the stack of disks called "stack breathing." Additionally, eccentricities and individual disk dynamics combined with the close spacing of the disks create problems in precisely identifying the disk to be selected Accordingly, a precise peripheral disk locator for selected. accurate record surface accessing is desired for improving throughput, that is, reducing the number of unsuccessful recording accesses into a stack of flexible record disks.